System of electrical distribution.



PATEN'IED MAY 26, 1903.

C. P. STEINMETZ. SYSTEM OF ELECTRICAL DISTRIBUTION.

APPLICATION FILED JAN. 2, 1901.

NO MODEL.

Witnesses Inventor. I

- Charles P Steinmetz b flM AC'C 0., WASHINGTON D c UNITED STATESPatented May 26, 1903.

PATENT OFFICE.

CHARLES P. STEINMETZ, OF SOHENEOTADY, NEW YORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

SYSTEM OF ELECTRICAL DISTRIBUTION.

SPECIFICATION forming part of Letters Patent No. 729,235, dated May 26,1903.

Application filed January 2, 1901. Serial No. 41,811. (No model.)

To to whom it may concern.-

Be it known that 1, CHARLES P. STEINMETZ, a citizen of the UnitedStates, residing at Schenectady, county of Schenectady, State of NewYork, have invented certain new and useful Improvements in Systems ofElectrical Distribution, of which the following is a specification.

I11 electrical tran smission-lines containing distributed capacity-such,for example, as underground or submarine cablesthe effect of anelectromotive force impressed upon the transmitting end of the line isnot felt immediately throughout the line. On the contrary, when currentcommences to flow into the transmitting end of the line it first chargesthat end of the line and then proceeds toward more and more distantportions of the line, charging each portion of the same as it proceeds,the propagation of current taking the form of a wave which traverses thetransmission-line from end to end.

If the electromotive force impressed upon the transmitting end of theline is alternating, then there will be a succession of waves followingeach other through the line, and if the line be long enough or, which isthe same thing, its distributed capacity be sufficient there may be oneor more complete waves of current in the transmission-line at any i11-stant. Such being the case, it is evident that the electromotive forceand current due thereto differ in phase and magnitude from point topoint along the length of the transmission-line. If, for example, theconstants of the line be such that when the electromotive force is at amaximum at the transmitting end of the line there occurs a point on thetransmission-line at which the electromotive force at the same instantis zero, then the electromotive forces at this point and at thetransmitting end of the line are in quadrature relation to each other.If this point mentioned is the first one at which the zero electromotiveforce occurs and if this point happens to be located at the receivingend of the line, then the line itself may be considered as correspondingto a quarter-wave length of the current supplied.

1 have discovered that if a line which possesses inductance as well asdistributed capacity in such magnitudes as to correspond thus to aquarter-wave length has impressed thereon at the transmitting end of theline an electromotive force of constant difference of potential, thenthe electromotive force at the receiving end of the line will be inquadrature with that impressed upon the line and will vary with the loadupon the receivingcircuit in such a manner as to maintain a constantvalue of current therein. It is obvious, of course, that thisarrangement may be reversed, one end of the line being supplied with aconstant current, the other end of the line then delivering a current atconstant potential.

The drawing illustratesmy invention in a general way, but cannot, ofcourse, be made to represent the relations between the various constantsof the line on which depend the operativeness of my invention.

Generally speaking, however, the invention comprises a source ofalternating electromotive force 1, preferably of constant potential,either single phase or multiphase, as may be desired. In the drawing,however, a singlephase source only is shown, this source beingoperatively connected in any suitable manner to a transmission-line2,possessing inductance and distributedcapacity, this line being madeup, for example, of underground cable of suitable length. The receivingend of the line is shown as consisting of a series circuit 3, iiicludingtranslating devices, such as arc-lamps or the like, this circuit beingconnected in operative relation to the transmission-lines 2, whichconstitute the medium for transferring energybetween theconstant-potential source 1 and the constant-current consumption orreceiving circuit 3.

If the resistance'of the transmissionline-may be neglected in comparisonwith the capacity and inductance of the same, then the relation betweenthe capacity and inductance necessary to produce a quarter-wave lengthbetween the transmitting and receiving ends of the line may berepresented by the equation LO=1/ (16 N where L represents thecoefiicient of self-induction, O the capacity, and N the frequency ornumber of waves per second of the impressed electromotive force of thegenerating source. As these are dependcut variables, thetransmission-lines may be designed in a large number of different ways,all of which may satisfy the above equation. No hard and fast rule cantherefore be given as to the precise amount of capacity or of inductancein the transmission-line, these qualities being dependent on thefrequency of the generating source, as will be evident. It is obvious,therefore, that my invention may as sume various forms without departingfrom the spirit thereof, for which reason'I desire my claims to be givena reasonably liberal construction.

That I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. The combination of a constant-potential circuit, a constant-currentcircuit, and a current-carrying medium electrically connecting saidcircuits in series, said medium having its electrical constants soproportioned as to antomatically transform current of the characterflowing in one of said circuits into current of the character flowing inthe other.

2. The combination of a constant-potential circuit, a constant-currentcircuit, anda current carrying medium connecting said circuits, saidmedium possessing distributed capacity and inductance in such magnitudesas to produce a quadrature relation between the electromotive forces insaid circuits.

The combination of a constant-potential circuit, a constant-currentcircuit, and a cable or cables having distributed capacity andconnecting said circuits, said cable or cables being proportioned so asto cause an automatic transformation of current of the character flowingin one of said circuits into cur rent of the character flowing in theother.

4:. The combination of a source of alternating current, a line connectedthereto and possessing inductance and distributed capacity in suchmagnitude as to produce a quadrature relation between the electromotiveforces at the beginning and end of the line respectively,

and a consumption-circuit connected to the end of said line.

5. The combination of a source of alternating current, a cable connectedto the terminals of the source and possessing such electrical constantsas to cause a phase displacement of ninety degrees between theelectromotive forces at the beginning and end of the cable respectively,and a constant-current circuit connected to the end of the cable.

6. The combination of a source of alternating current, cablesoperatively connected to the terminals of said source, and to aconstantcurrent circuit, said cables possessing capacity and inductancein such relative magnitude as to produce a quadrature relation betweenthe electromotive force impressed upon the cable and that impressed uponthe constant-current circuit.

7. The combination of a constant-poten tialcircuit, a constant-currentcircuit, and a cable or cables connecting said circuits, said cable orcables being of negligible resistance and possessing distributedcapacity and selfinduction in the magnitudes expressed by the equationLC=1/(16 N where L and C represent respectively the self-induction andcapacity and N the frequency.

8. The combination of a source of alternating current, a consumptioncircuit, and a cable or cables operatively connected to saidconsumption-circuit and to said source, said cable or cables possessingdistributed capacity in such magnitude relatively to selfinduction ofthe system as to produce a con* stant current in said consumptioncircuitwhen the electromotive force of said source is constant.

In witness whereof I have hereunto set my hand this 29th dayof December,1900.

CHARLES 1. STEINMETZ.

Vitnesses:

BENJAMIN B. HULL, MARGARET E. WooL'LEY.

